libsigrokdecode has had support for the jitter protocol decoder for a while now (it is already shipped with the recently-released libsigrokdecode 0.3.1), but this hasn't been officially announced yet, so here goes.

The decoder allows you to retrieve the timing jitter between two digital signals. This can be useful for a number of things, e.g. finding jitter/delay between a sender and receiver (be it wired or over some form of wireless communication), or for debugging your firmware interrupt setup by checking how much jitter you have between multiple consecutive invocations of the interrupt handler that should in theory always be equally spaced.

We also added a small test-case in our sigrok-test repository so we can ensure that the PD works fine (and continues to do so upon changes).

This protocol decoder has been contributed by Sebastien Bourdelin, thanks a lot!

This is mostly a bugfix-release, the C library API was not changed. This means existing frontends that work with / are linked against libsigrokdecode 0.3.0 will continue to work just fine, without requiring relinking or recompiling.

However, some of the protocol decoders' output changed in ways which are not compatible with the state of the decoders in the last libsigrokdecode release. This means, if you're using any scripts to parse decoder output, or if you have any "private" protocol decoders that stack on top of one of those shipped with libsigrokdecode, you will have to do some adaptations. You're also encouraged to submit such decoders to be included in libsigrokdecode proper, of course!

In addition to all kinds of improvements and bugfixes in existing protocol decoders (PDs), you're probably most interested in what new protocol decoders are now supported (backported from git HEAD). So here's the list:

Please check the libsigrokdecode NEWS file for the full list of user-visible changes in this release. As always, we're happy about bug reports, feature suggestions, comments about which protocol decoders you'd want supported next, or even better — patches :)

It's been a while since the eeprom24xx protocol decoder was added to libsigrokdecode, but there hasn't been an "official" announce yet, so here goes.

The eeprom24xx PD can decode the I²C-based protocol of (almost) all 24xx series EEPROMs from various vendors.

Supported chips include for example the Microchip 24LC64 or 24AA025UID, the ST M24C01 or M24C02, the Siemens SLx24C01 or SLx24C02, and others. Various other chip families can be added relatively easily via chip spec entries in the decoder's lists.py file.

These ICs usually have only very few bytes of storage (e.g. 128 or 256 bytes), where the memory is organized into pages (the page size is e.g. 8 or 16 bytes). They usually support various types of accesses (command sequences) such as "byte write", "page write", "current address read", "random read", "sequential random read", "sequential current address read", and others.

Apart from a common command subset, some of the chips also support custom non-standard commands such as "set write protection" or "read write protection status" (on ICs that have write-protectable areas), and some others.

It's a USB-attached device (uses one of the WCH CH9325 ICs commonly found in UNI-T gear) that can measure RPM and counts.

The protocol of the device (now documented in the sigrok wiki) was reverse engineered by Mike Walters, using a somewhat unusual and quite interesting technique. Instead of the usual method of sniffing the USB traffic and then staring at hex numbers until things start to make sense, he used the following method:

After a first quick look at the USB traffic it was pretty clear that the packets usually look something like this:

070?<3=7<60655>607;007885

Now, instead of trying to figure out which bit and byte means what by looking at many of these packets, Mike instead generated his own packets that looked like the real packets from the UT372. He sent them to the vendor's PC software (via a custom-built "emulator" on a USB-enabled Arduino), which then interpreted and displayed the values and flags that it thought were sent by an actual UT372 device.

By randomly flipping bits in these packets and observing how the PC software's interpretation of the packets differed, Mike was able to figure out the individual protocol details a lot faster than using other methods.

Shortly after the protocol was known, Martin Ling wrote a libsigrok driver for the UT372 by hooking up a device-specific ut372 parser to the existing uni-t-dmm driver in libsigrok (which already handles the somewhat "special" CH9325 details).